Because of their potency and excellent safety profile, human monoclonal antibodies (mAbs) are leading candidates for the generation of specific, but mechanistically diverse microbicides. This Project focuses on the critical path development of mapp66, a combination of human mAbs, to prevent sexual transmission of HIV and HSV. mapp66 is manufactured in a transient expression system (Nicotiana) that is appropriate for large, cost-sensitive markets. The prototype mAbs in mapp66 are well-characterized and bind to antigens recognized as appropriate targets: (a) glycoprotein D on HSV;(b) gp41 on HIV;(c) gpl20 on HIV. Mucosal and systemic vaccines that are based on anti-idiotype mAbs of mapp66 are being developed independent of this project, but in parallel to enhance antibody-mediated protection via active immunization. The overall goal of the Critical Path Project is to submit an Investigational New Drug application (IND) to support evaluation of a vaginal film formulation of mapp66 in human volunteers. In specific aim 1 Nicotiana manufactured IgG1 and lgG2 versions of the mapp66 anti-HSV and anti-HIV mAbs are produced aglycosylated or with homogenous mammalian glycans. The mAbs are evaluated for a range of parameters to maximize the likelihood of successful industrialization. Parameters evaluated are: expression, stability, neutralization, mucus trapping of virus, complement fixation and Fc gamma receptor binding. In specific aim 2 the mapp66 mAbs selected from Aim 1 are expressed using the Nicotiana manufacturing system. Purified mAbs are spray-dried and used for developing a vaginal film formulation. Activities culminate with GMP manufacturing of spray-dried active pharmaceutical ingredient (API) and vaginal film (drug product) for IND-enabling preclinical safety and efficacy studies. In specific aim 3 IND-enabling studies are performed characterizing the mapp66 in vitro, in animal efficacy models and in pharmacology/toxicology studies. An IND on mapp66 film is prepared to support safety testing in human volunteers. In addition to conducting Critical Path studies and addressing regulatory requirements, the mapp66 mAbs are provided to other Projects for hypothesis-driven research into the interactions of HIV and HSV mAbs with the cellular and host defenses in the cervicovaginal environment.